a[101][20001]={{1}};i,j,n,s;main(k){for(scanf("%d%d%d",&n,&s,&k);++i<=n;)for(j=0;j<=2e5;j++)a[i][j]=(a[i-1][j]+a[i][j-i]*!(j<i))%1000000007;i=!printf("%d",a[n][s-n*(n-1)/2*k]);}